The Nephrology Radioimmunoassay Laboratory will: (1) provide investigators with analyses utilizing radioimmunoassay techniques that are necessary for the conduct of their research; (2) provide standardized procedures and quality control; (3) provide a central facility for processing and storing samples; and (4) provide a resource which will facilitate new methods that investigators deem necessary to attain the stated goals for each project. The core will be utilized by Projects 1, 2, 3, 4, 6, 7, 8 and 9.